Base16 Speed

Base16 conversion from printable characters to binary data, and back again, is
important for one project I work on. Doing conversion as fast as possible is a
good thing.

I had some code that did the binary to printable characters conversion well
enough, using sprintf(), but I thought it wasn’t optimal, so I decided to find
out.

I wrote some quick and dirty code, in my github, to test the
performance difference between using sprintf() and using a lookup table.
Turns out, the LUT is about 10 times faster on my Core-i7 and about 14 times
faster on a BeagleBone. That’s quite an improvement!

I’m sure there’s an even faster way to do other things my code does less than
optimally, now I’m on the hunt!